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Патент USA US2405906

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Patented Aug. 13, 1946
Hans Schindler, Evanston, ‘and ‘Lawrence M.
Henderson, Winnetka, Ill.,'fassignors to The
Pure Oil Company, Chicago, Ill., acorpora
tion of Ohio
No Drawing. Application May 21, 1943,‘
Serial No. 487,970
12 Claims.
(01. 252-59)
This invention relates to improvements in tur- 1. 3 therefore these acids must be removed’ from
bine oils and more particularly relates to turbine
oils having improved resistance to oxidation and
to inhibitors for preventing rust formation of
steam turbines.
the acid oil. The removal of the corrosive acids
may be accomplished in several ways. For exam
ple, in' the neutralization of the spent caustic
solution, the neutralization may be regulated so
that addition of acid to the spent alkali is stopped
when the pH value of the solution reaches 8.
At‘ pH‘of 8, acid oil separates from the spent
caustic solution which contains the desirable in
10 hibiting constituents while the undesirable cor
It has been found that rust formation and cor- j
rosion of the working parts of steam turbines
occurs when lubricated with ordinary mineral
oils. We have found that the deterioration of
turbine oils and rusting of the turbines can be
materially inhibited by adding to mineral turbine
oils a small amount of “acid oil” obtained by
: rosive compounds remain in the aqueous phase.
Instead of partially neutralizing the spent al
neutralizationof spent caustic alkali solutions
kali solution, it may be completely neutralized
resulting from the treatment of straight-run and
with sulfuric or other acidic material to spring
cracked light petroleum distillates such as kero-' 15 all the acid oil from the solution and the total
sene and gasoline with caustic alkali solution to
acid oil may be carefully neutralized with alkali
remove therefrom sulfur compounds, phenolic
such as sodium or potassium hydroxide or car
compounds and acids.
bonate until a pH of 8 is reached. The portion
,of the acid oil which does not go into aqueous
20 solution is retained as the desired inhibitor.
Another object of our invention is to provide
The corrosive acids can also be eliminated from
a method for inhibiting turbine oils against oxi
the acid oil by thorough washing with water.
An object of our invention is to provide an
improved turbine oil.
dation while in use.
The corrosive acids .are more soluble in water
A further object of our invention is to provide
than are the desirable inhibiting compounds in
an inhibitor suitable for inhibiting oxidation of 25 the acid oil. Where‘water washing is relied upon
mineral oils and rusting of steam turbines.
to remove the corrosive acids, the proportion of
Further objects of the invention will appear
water to acid ‘oil may vary from 5 to 50 volumes
from the following description.
In accordance with our invention used caustic
alkali solution, which is partially or substantially
of water to one‘volume of acid oil and washing
is preferably carried out‘ in a multiple stage
completely spent, resulting from the treatment .
Another method for removing corrosive acids
of straight-run and/or cracked gasoline and/or
from the acid oil is to distill the acid oil at a
kerosene fractions of mineral oil, is partially or
temperature up to approximately 175° C. At this
completely neutralized by means of acid, acid
temperature the low boiling acids, such as formic,
anhydride or acid reacting salt to spring the 35 acetic and propionic acids distill overhead with
“acid oil.” The “acid oils” which we have found " ' out any substantial loss of oxidation and rust
to be e?icacious as inhibitors are those sprung
inhibiting compounds. The residue may then be
from used aqueous alkali solutions resulting from
Washed with water.
the treatment of petroleum distillates contain‘
' Acid oil, free of readily water soluble corrosive
ing phenolic bodies such as phenol, cresol, poly 40 acids, may be used as such in small amounts in
hydroxy benzene ring compounds and thio- '\
cresols, as well as sulfur compounds such as mer
captans. Extraction of distillates with aqueous
mineral oil. However, unless the acid oil is
treated as hereinafter described, it may cause
resin-like deposits to form on the surfaces which
solutions of sodium or potassium hydroxide re
it contacts. In order to avoid the possibility
sults in the removal of the aforesaid compounds 45 of resin deposition,‘ we extract the acid oil with
from the distillate in the form of the alkali metal '
a light water immiscible solvent such as hexane,
reaction compound dissolved in the caustic alkali
benzene, and light petroleum naphtha in which
solution. As used in the claims “acid oil” shall
the acid oil is soluble and which has a boiling
mean the product just described.
point su?iciently low to enable it to be readily
In addition to the aforesaid compounds, the 50 removed from the acid ‘oil by distillation. The
acid oil may contain low boiling fatty acids such
ratio of acid oil to solvent used in the extraction
as formic, acetic and propionic, as well as naph
thenic acids which were present in the petroleum
distillate. The low-boiling acids are harmful in
that they cause corrosion of steam turbinesand 55
may vary over wide limits. We have found aratio
of one volume of acid to from one to three to five
volumes of solvent to be satisfactory. The result
ing extracted acid 011, after removal 0f;the sol
with the method just described did not include a
step of water; washing, we prefer to water wash
vent, may be added to mineral} oil in amounts of
from about .05 to 2% by volume of the oil. The
resulting o-il should be permitted to stand for a
the acid oil. In our preferred method, the acid
oil resulting from neutralization to pH of 8 is
period of several hours or more since a precipitate
sometimes ‘forms ‘which should be removed by (Fl dispersed in approximately two volumes of wa
ter and the aqueous soléution is, then neutralized
decantation, iilte‘rin‘g and/or centrifuging before
to pH of 7 and extracted with a water immiscible
solvent such as those previously set forth. The
desired inhibitor will be extracted in the form of
vention, spent caustic SOda resulting from the
treatment of a blend of straight-run and cracked 10 a solution in the solvent from which the solvent
can be removed by distillation and/ or fractiona
gasoline from a high pressure thermal pracking
using the oil.
In order to demonstrate the utility of our in
operation with aqueous caustic'soda solution con
taining approximately 10% by weight of sodium
hydroxide was neutralized with concentrated sul
‘tic-n. .
It is to be'understood that our invention is not
limited to the inhibition of the speci?c oil used in
furic acid until the pH of the solution was 8,‘ An 15 the tests but is applicable in general to various
acid 011 separated which was extracted witntnree , -‘ types of steam turbine oils and steam turbines.
It should be understood that the inhibitor can be
volumes of hexane. Five-tenths per cent by’y‘ol
p'repared'from spent aqueous and alcoholic alkali
metal hydroxide solutions.
ume of the resulting acid oil was added to Mid
Continent neutral mineral oil having the fol
20' We claim:
lowing ‘characteristics. " '
1. The method of preparing anoxidation and
rust inhibitor for mineral turbine oils comprising
Table ‘I
Viscosity, Saybolt, at 100° 5:...
recovering from used aqueous caustic alkali so
Pour point _________________ __ 251E‘. maximum
Color N. RA ___________ __>____ , 21/2 maximum
lution resulting from the treatment of low-boil
25 ing hydrocarbon distillates containing sulfur and
phenolic compounds with aqueous caustic alkali
solution, by neutralization with 'an ‘acidic sub
stance the entire portion of “acid oi'l” substane
Another sample was made ‘in the same manner
tially free from constituents soluble in aqueous
containing .1% ‘of the acid oil. The two blends ' solution of approximately pH 8, extracting said
were subjected to the ‘.BrowneBoveri ‘oxidation 30 portion of the “acid oil” with a hydrocarbon
test ‘and the following results obtained.
solvent boiling below the boiling range ‘of the
Demulsibility at 130° F_____ _r_
1,259 minimum
Demulsibility at 100? F ______ __ v
1500 minimum
extractable portion of the "acid oil” and-‘separat
Table I I .
ing- the extract from the solvent.
, Sludge, mg.
which the solvent is hexane.
Mineral oil (without acid oil)_____ »
Mineral oi] plus .5% acid oil ___________ _-_ ________ __
55. 7
28. 5
Mineral oil plus .l% ‘acid'oiL _'_;_ ____ -_
25. 2
The sample ‘containing .'5'% by volume of ‘acid
_2. The method in accordance with claim 1 in
3. The method in accordance with claim 1 in
which said portion of “acid oil” is dispersed in
water, the aqueous dispersion neutralized ‘with
40 acid to a pH of f7 and the resulting ‘dispersion
‘extracted with the hydrocarbon solvent.
'oil was subjected ‘to'the tentative A. S. T. Mjmeth
4. Method in accordance with claim 1 in which
od D-665-42T ‘for testing ‘rust ‘preventing "char
the used caustic alkali solution is neutralized in
‘the presence of water to a point 'Where the aque
‘acteristics , of steam ‘turbine ‘oil in the presence
‘of water. This method is published in A. S. T. M. 45 ous solution ‘has a pH of approximately 8, and
Standards on Petroleum Products and Lubricants
vthe “acid oil” which separates is extracted with
'iorOctob'er 19, 1942. A test 'stripwas obtained
the hydrocarbon solvent.
which had a. rating of 5—. A ‘perfectfstrip {would
5. Method in accordance with vclaim 1 in which
have a rating of 5. The test 'w‘as'conductedover
'tlie'used caustic alkali is completely ‘neutralized,
a period of 48 hours. No water separated from
‘the separated “acid oil” v‘is then neutralized with
the oil at the conclusion of the test and the'oil 50 ‘alkali in the presence of water until the ‘aque
ous layer has a pH of approximately 8 and the
A Bro'wn-Boveri oxidation test was ‘made on
‘resulting “acid oil” is extracted with the hydro
oil made as aforesaid with the exceptionthat it 55 6. Method in accordance'with claim '1 in which
was not extracted with hexane. A comparison of
the constituents soluble ‘in aqueous ‘solution of
the results of the oil with and without inhibitor
‘pH 8 are removed from the “acid oil” by dis
are given in the following table.
tilling it at a temperature or approximately 175°
F. and then Washing the residue with water.
Table III 7
the same oil containing .1% by volume of the acid
Sam le
Sludge . . in er,
amount of the entire portion of “acid oil” solu
test 7
Mineral oil (without acid oil) __
55. 7
Mineral oil (plus 0.1% by wt.
‘of acid oil) ______ _; _____ _.‘__'__
+3 Too dark
'0. 26
‘0. 13
7. The method in accordance with claim 1 in
which the “acid oil” is washed with water prior
to extraction with the hydrocarbon ‘solvent.
8. A mineral turbine oil containing a small
Although the acid oil without hexane ‘extrac
tion appears to be a better oxidation-inhibitor
than the vacid oil’aft'er hexane extraction, it was
less desirable because it caused a're'sin-like de
posit to form on thete‘st ‘strip. This vobjectionable
‘feature is 'obviated'by the extraction.
Although the acid oil prepared in accordance 75
ble in 10% aqueous sodium hydroxide solution
vsubstantially insoluble in ‘aqueous solution'having
a pH of 8 and completely soluble in hexane, the
amount of “acid “oil” present in the mineral oil
being suf?cient to‘inhibit deterioration ofthe oil
and inhibit rusting ‘of steam ‘turbines when the
oil isused for lubrication thereof.
J9. Mineral'oil in accordance with claim 8 in
‘which the amount of “acid oil” contained there
7in ranges from ‘approximately f0'5'% to ‘2% by
10. The method of preventing rusting of steam
turbines which comprises lubricating the turbines
with a mineral lubricating oil containing a small
amount of the entire portion of “acid oil” solu
ble in 10% aqueous sodium hydroxide solution
substantially insoluble in aqueous solution of DH
8 and completely soluble in hexane, the amount of
“acid oil” present in the mineral oil being suf
entire resulting "acid oil” with approximately 3
volumes of hexane and separating the extract
from the hexane.
12. The method of preparing an oxidation and
rust inhibitor comprising washing gasoline distil
late, containing sulfur compounds, phenolic com
pounds and other acidic compounds, with aqueous
caustic alkali solution, neutralizing the resulting
?cient to inhibit deterioration of the oil and to
alkali solution with an acidic reagent in the pI'eS
inhibit rusting of steam turbines when the oil 10 ence of water to a point where the aqueous layer
is used for lubrication thereof.
has a pH of approximately 8, separating “acid
11. The method of preparing an oxidation and
oil” from the aqueous layer, dispersing the entire
rust inhibitor which comprises washing a mix
resulting “acid oil” in water and neutralizing the
ture of straight run and cracked gasoline contain
dispersion until the water layer has a pH of 7,
ing sulfur, phenolic and other acidic compounds,
with aqueous alkali solution of approximately
10% by weight concentration, neutralizing the
extracting the resulting oily layer with a hydro
carbon solvent having a boiling point below the
boiling range of the oily layer and separating the
resulting alkali solution with an acidic reagent
extract from the solvent.
until the aqueous layer has a pH of 8, separating
“acid oil” from the aqueous layer, extracting the 20
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